**Core Concept**
Transamination is a crucial reaction in amino acid metabolism, catalyzed by transaminase enzymes (also known as aminotransferases). Vitamin B6, specifically pyridoxal phosphate, serves as a coenzyme for these enzymes, facilitating the transfer of an amino group from an amino acid to a keto acid. This reaction is essential for the synthesis and degradation of amino acids.

**Why the Correct Answer is Right**
The transamination of α-ketoglutarate involves the transfer of an amino group from an amino acid (in this case, glutamate) to α-ketoglutarate, resulting in the formation of glutamine. However, since the question specifically asks for the amino acid formed from transamination of α-ketoglutarate, we need to consider the reverse reaction. In this case, the amino acid formed from the transamination of α-ketoglutarate is actually glutamate. However, considering the reverse, the amino acid formed from α-ketoglutarate is actually glutamine's precursor in transamination reactions. The correct answer is glutamate's amino group donor in transamination reactions, which is actually **glutamate** itself. However, it is more likely the question is referring to the product of transamination of α-ketoglutarate, which is actually glutamate.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question.
**Option B:** This option is incorrect because it is not the product of transamination of α-ketoglutarate.
**Option C:** This option is incorrect because it is not the correct answer.

**Clinical Pearl / High-Yield Fact**
Transamination reactions are essential for maintaining amino acid homeostasis in the body. These reactions are crucial in the context of amino acid metabolism, and understanding the role of vitamin B6 in these reactions is vital for diagnosing and managing disorders related to amino acid metabolism.

**Correct Answer: C. Glutamate.**